vasprintf_chk.c

/* Copyright (C) 1995,1997,1999-2002,2004,2006,2008 Free Software Foundation, Inc. This file is part of the GNU C Library. The GNU C Library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. The GNU C Library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with the GNU C Library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. As a special exception, if you link the code in this file with files compiled with a GNU compiler to produce an executable, that does not cause the resulting executable to be covered by the GNU Lesser General Public License. This exception does not however invalidate any other reasons why the executable file might be covered by the GNU Lesser General Public License. This exception applies to code released by its copyright holders in files containing the exception. */#include <malloc.h>#include <string.h>#include <stdio.h>#include <stdio_ext.h>#include "../libio/libioP.h"#include "../libio/strfile.h"int
__vasprintf_chk (char **result_ptr, int flags, constchar *format,
va_list args)
{
/* Initial size of the buffer to be used. Will be doubled each time an overflow occurs. */const _IO_size_t init_string_size = 100;
char *string;
_IO_strfile sf;
int ret;
_IO_size_t needed;
_IO_size_t allocated;
/* No need to clear the memory here (unlike for open_memstream) since we know we will never seek on the stream. */string = (char *) malloc (init_string_size);
if (string == NULL)
return -1;
#ifdef _IO_MTSAFE_IO sf._sbf._f._lock = NULL;
#endif _IO_no_init ((_IO_FILE *) &sf._sbf, _IO_USER_LOCK, -1, NULL, NULL);
_IO_JUMPS ((struct _IO_FILE_plus *) &sf._sbf) = &_IO_str_jumps;
_IO_str_init_static_internal (&sf, string, init_string_size, string);
sf._sbf._f._flags &= ~_IO_USER_BUF;
sf._s._allocate_buffer = (_IO_alloc_type) malloc;
sf._s._free_buffer = (_IO_free_type) free;
/* For flags > 0 (i.e. __USE_FORTIFY_LEVEL > 1) request that %n can only come from read-only format strings. */if (flags > 0)
sf._sbf._f._flags2 |= _IO_FLAGS2_FORTIFY;
ret = INTUSE(_IO_vfprintf) (&sf._sbf._f, format, args);
if (ret < 0)
{
free (sf._sbf._f._IO_buf_base);
return ret;
}
/* Only use realloc if the size we need is of the same (binary) order of magnitude then the memory we allocated. */
needed = sf._sbf._f._IO_write_ptr - sf._sbf._f._IO_write_base + 1;
allocated = sf._sbf._f._IO_write_end - sf._sbf._f._IO_write_base;
if ((allocated >> 1) <= needed)
*result_ptr = (char *) realloc (sf._sbf._f._IO_buf_base, needed);
else
{
*result_ptr = (char *) malloc (needed);
if (*result_ptr != NULL)
{
memcpy (*result_ptr, sf._sbf._f._IO_buf_base, needed - 1);
free (sf._sbf._f._IO_buf_base);
}
else/* We have no choice, use the buffer we already have. */
*result_ptr = (char *) realloc (sf._sbf._f._IO_buf_base, needed);
}
if (*result_ptr == NULL)
*result_ptr = sf._sbf._f._IO_buf_base;
(*result_ptr)[needed - 1] = '\0';
return ret;
}
libc_hidden_def (__vasprintf_chk)